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The verification of mathematical models for multistage reciprocating compressors is crucial for ensuring their accuracy and reliability. In this study, we used different machine learning (ML) models to verify the results of MATLAB-based models of single-stage reciprocating compressors, multistage reciprocating compressors without intercoolers, and multistage reciprocating compressors with intercoolers to simulate the real-world operating conditions of a reciprocating compressor. The verification focuses on key performance indicators, such as the pressure–volume (PV) graph, outlet temperature graph, volumetric efficiency, and pressure ratio graph. The MATLAB model computes thermodynamic parameters, such as the power required, outlet pressure, and outlet temperature for various operating conditions. The MATLAB model produced the following results for single-stage compressor: the outlet pressure increased by 1.6 times the inlet pressure of the compressor, the volume reduced by 20% of the volume at the inlet of the single-stage compressor, and the outlet temperature increased by 30% of the inlet temperature. In the case of a multistage compressor without an intercooler, the outlet pressure increased by about 3.3–3.6 times the inlet pressure of the compressor; the volume reduced by 60% of the volume at the inlet, and the outlet temperature increased by 35% in comparison to the inlet temperature of the multistage compressor without an intercooler. Subsequently, in the case of a multistage compressor with an intercooler at the first stage of compression, the pressure increased by three times the inlet pressure; at the second stage of compression, the pressure increased by six times the inlet pressure of the compressor, the volume was reduced by approximately 80%, and the intercooler maintained the increase in outlet temperature by 30%, limiting it and preventing excessive expansion of air in the compressor and increasing the efficiency of the compressor by 12% in comparison to the multistage compressor without an intercooler. In addition, the results generated by all the machine learning models used in the study were in correlation with the results generated by the MATLAB model for all three compressors, with an accuracy of approximately 90% or more for almost all the models implemented for prediction. By comparing the predicted outputs from the ML model with the MATLAB-generated results, the accuracy and consistency of the simulation were assessed. This study aims to bridge the gap between traditional mathematical modeling and modern data-driven validation techniques to ensure robustness in compressor performance predictions.

This study was aimed to evaluate the effect of blending two types of alcohol with pure diesel fuel. A 4-cylinder 4- stroke water cooled direct injection (DI) diesel engine was used. An electric dynamometer was connected to the engine to make load by electric heaters; the load on the engine was fixed at full load. The engine was run with two speed levels : 1300 rpm and 1600 rpm.  Three types of fuel were used, including blended n- butanol (B) and Acetone(A) mixed with diesel by two levels named by AB15D85 and AB30D70, respectively, and compared with pure diesel fuel (D), which was the baseline.  Gas emission was measured by using gas analyzer type AirRex - HG540. Results obtained from the experiment were statistically analyzed and showed that brake thermal Efficiency registered a slight increase of 5.7% when using(AB30D70) compared with base diesel fuel, while the samples (AB30D70, AB15D85)   pointed to a slight increase in BSFC by (5.1%and4.4%) respectively when compared with base diesel fuel. The fuel(AB30D70) detected a sharp reduction in both carbon dioxide (CO2) unburned hydrocarbon(HC) and Nitrogen oxides (NOx) by (49.1%,100%, 38%) respectively   compared with base diesel fuel

Pearson considers a few aspects of positive displacement compressors, meaning those that work by reducing the volume of a trapped quantity of gas. There are two key numbers that describe the performance of a positive displacement compressor: the isentropic efficiency and the volumetric efficiency. When talking about \"the efficiency\" of a compressor it is important to know which one is being discussed. They are as different as \"miles\" and \"gallons\"--both contribute to the miles per gallon figure for your car, but it doesn't make sense to say how many gallons you drive to work each day or how many miles you bought at the gas station. The isentropic efficiency is a measure of how well the compressor performs compared to an ideal machine and is defined as the work done in an ideal machine (when there is no increase in entropy) divided by the work done in the actual machine (where irreversible losses such as friction and turbulence cause the entropy to increase).

In this paper, the optimization of a gear pump after tooth root undercutting has been investigated; this requires the volumetric, mechanical and total efficiencies of the pump to be calculated. Due to conflict in the existing model, the total efficiency is often calculated with the assumption that the other efficiencies have acceptable values. Multiple-dimensional logical functions are an additional independent method that can be used for the optimization of a pump.

This paper addresses the computational fluid dynamics (CFD) simulation to investigate the in-cylinder flow characteristics of 2D combustion chamber for a hydrogen-fuelled four-stroke internal combustion engine. CFD simulation has been carried out using commercial CFD codes. The engine speed was varied from 1000 to 3000 rpm, the range of equivalent ratio from 0.6 to 1.0 and the crank angle from 0 to 720 degrees in this study. The effect of the engine speed and equivalence ratio on the flow-field characteristics and volumetric efficiency are investigated in the motoring condition. The increase of engine speed gives a more efficient diffusion process for hydrogen and gives a more homogeneous air–fuel mixture structure. The characteristics of the flow-field are represented by the in-cylinder pressure and temperature distribution as well as the contours of the hydrogen mass fraction for different engine speeds. The acquired results show the maximum in-cylinder temperature and pressure obtained of 650 K and 1.143 MPa at the engine speed of 3000 rpm respectively. It can be seen that the engine speed and equivalence ratio are strongly related to the volumetric efficiency. The results show that the volumetric efficiency increases linearly with increase of the engine speed, but decreases with increase of the equivalence ratio. The results obtained from the simulation can be employed to examine the homogeneity of the air–fuel mixture structure for a better combustion process and engine performance.

Dielectric ceramics are highly desired for electronic systems owing to their fast discharge speed and excellent fatigue resistance. However, the low energy density resulting from the low breakdown electric field leads to inferior volumetric efficiency, which is the main challenge for practical applications of dielectric ceramics. Here, we propose a strategy to increase the breakdown electric field and thus enhance the energy storage density of polycrystalline ceramics by controlling grain orientation. We fabricated high-quality -textured Na 0.5 Bi 0.5 TiO 3 –Sr 0.7 Bi 0.2 TiO 3 (NBT-SBT) ceramics, in which the strain induced by the electric field is substantially lowered, leading to a reduced failure probability and improved Weibull breakdown strength, on the order of 103 MV m −1 , an ~65% enhancement compared to their randomly oriented counterparts. The recoverable energy density of -textured NBT-SBT multilayer ceramics is up to 21.5 J cm −3 , outperforming state-of-the-art dielectric ceramics. The present research offers a route for designing dielectric ceramics with enhanced breakdown strength, which is expected to benefit a wide range of applications of dielectric ceramics for which high breakdown strength is required, such as high-voltage capacitors and electrocaloric solid-state cooling devices. The energy density of dielectric ceramic capacitors is limited by low breakdown fields. Here, by considering the anisotropy of electrostriction in perovskites, it is shown that -textured Na 0.5 Bi 0.5 TiO 3 –Sr 0.7 Bi 0.2 TiO 3 ceramics can sustain higher electrical fields and achieve an energy density of 21.5 J cm −3 .

An experimental study on four electric gear urea pumps was carried out, and the variation rules of supply flow rate, speed, and volumetric efficiency of the urea pumps were obtained. Test results show that the volumetric efficiency will be affected by the coupling of multiple factors simultaneously, showing complex nonlinearity. A simulation model whose accuracy was verified by test data was established for analyzing the influencing factors of supply performance. With the increase in speed, the variation of volumetric efficiency has a linear relationship with the change of radial clearance and a quadratic parabola relationship with the change of axial clearance. In the range of working speed, the influence of radial clearance on volumetric efficiency is more significant, while the influence of axial clearance on volumetric efficiency will be gradually enhanced with increasing speed. The radial tolerance range should be as small as possible to ensure the consistency of the urea pump’s volumetric efficiency.

The energy transition demands highly efficient pumps for fluids handling in energy systems. Screw-type volumetric pumps typically exhibit stable and high efficiency even when operating far from their design point, representing a promising technological solution, especially for challenging engine cooling applications. In this paper, the model-based design of a high-speed twin-screw pump optimized for internal combustion engine cooling applications was developed. A zero-dimensional mathematical model previously developed to evaluate the performances of triple-screw pumps was adapted to design twin-screw pumps with an improved screw shape. Thanks to the model, the screw geometry was optimized for maximizing the pump volumetric performance, while fulfilling strict design criteria in terms of overall dimensions, revolution speed, and external gearing for the screws drive. The operating high speed favored an easy potential substitution of the more conventional centrifugal pumps. In this case, the efficiency is highly dependent on the revolution speed which significantly changes, being the pump mechanically linked to the crankshaft. A prototype of the twin-screw pump was built and tested in a wide operating range. An efficiency close to 50% even at high revolution speeds (3000 rpm) was achieved. The limited dependence of the efficiency from the revolution speed was also observed. Moreover, a significant improvement of the volumetric efficiency (10%) at design point compared to a twin-screw pump with a not optimized screw geometry was also remarked. These promising results testify the good potential of twin-screw pumps to improve the efficiency of engine cooling systems, enabling significant energy savings.

A three-dimensional unsteady CFD model was developed to investigate leakage behavior within the compression compartments of a scroll-type compressor used in automotive air-conditioning systems. The effects of variations in axial and radial gaps on volumetric and isentropic performance were examined, along with the transient evolution of temperature and pressure within the compression zones. The results show that, when the axial spacing is kept at 0.02 mm, enlarging the radial gap from 0.02 mm to 0.05 mm reduces volumetric efficiency from 95.68% to 93.09% and lowers isentropic efficiency from 85.67% to 80.38%. Conversely, with the radial clearance maintained at 0.02 mm, increasing the axial gap to 0.05 mm decreases volumetric efficiency from 95.68% to 84.10%, while isentropic efficiency drops from 85.67% to 69.13%. As both clearances increase, the average mass flow through the compressor’s suction and discharge ports gradually declines. It is evident that the axial spacing has a stronger influence on overall compressor performance, highlighting the importance of precise control of the axial gap to ensure stable and reliable operation.

The volumetric and hydro-mechanical efficiencies describe the performance of external gear machines (EGMs), pumps and motors. In the last decades, several lumped parameter models have been designed to simulate EGMs and predict their efficiencies. The early works have focused on the prediction of the volumetric efficiency, and only in the last years have several models capable of predicting the hydro-mechanical efficiency been developed. The purpose of this work is double. 1) Provide an overview of the approaches developed and used by other authors to compute the hydro-mechanical efficiency with a lumped parameters model. 2) Show the capability of a lumped parameters model to compute the main sources of internal forces and resistive torques in an external gear pump (EGP). The torque losses considered are the viscous contributions on the tooth tip, on the gear sides, and within the journal-bearings, and the torque loss due to the gears mesh. In the present work a 20 cm3/rev EGP with a maximum operating pressure of 240 bar is analysed. Lastly, the results of the numerical model are compared with the ones returned by the experimental characterisation of the pump and by a 3D CFD model developed in the Simerics MP+ environment.